Bloody Diarrhea
Blood + WBC  in stool	·       Salmonella: poultry ·       Campylobacter: most common cause, associated with GBS ·       E. coli 0157:H7—hemolytic uremic syndrome (HUS) ·       Shigella: second most common association with HUS ·       Vibrio parahaemolyticus: shellfish and cruise ships ·       Vibrio vulnificus: shellfish, history of liver disease, skin lesions ·       Yersinia: high affinity for iron, hemochromatosis, blood transfusions ·       Clostridium difficile: white and red cells in stool
Dx	·       best initial test is blood and/or fecal leukocytes ·       Stool lactoferrin has greater sensitivity and specificity compared with stool leukocytes. ·       The most accurate test is stool culture.
Tx	depends on 👾

Giardiasis
RF	Exposure to contaminated food or water Fecal incontinence & crowding (eg, daycare, nursing homes)
Clx	Acute o Loose, foul-smelling, fatty stools o Abdominal cramps o Flatulence o Weight loss Chronic o Malabsorption (eg, lactose intolerance) o Profound weight loss o Vitamin deficiencies
Tx	Metronidazole

Vibrio vulnificus
#	·       Gram-negative, free-living in marine environments ·       Ingestion (oysters) or wound infection ·       ↑ Risk in those with liver disease* (cirrhosis, hepatitis)
S/s	·       Rapidly progressive (often <12 hours) ·       Septicemia – septic shock, bullous lesions ·       Cellulitis – hemorrhagic bullae, necrotizing fasciitis
Dx	Blood & wound cultures
Tx	IV ceftriaxone + doxycycline
*Hereditary hemochromatosis is particularly high risk as iron acts as a growth catalyst.

Typhoid fever
	Usually presents in a progressive manner
S/S	1st week: Fever. 2nd week: Abd pain + salmon-colored rash. 3rd week: HSM + Abd complications (bleeding – perforation).

	Clostridium difficile colitis
RF	Recent antibiotics / Hospitalization
Path	·       Disruption of intestinal flora  → C difficile overgrowth ·       Exotoxins cause mucosal inflammation/injury
Clx	Watery diarrhea (most common) Fulminant colitis/toxic megacolon (emergency 🚨)
Dx	Stool PCR
Tx	Oral metronidazole or vancomycin

Viral Hepatitis
👾	·       Hep A: Feco-oral ·       Hep B + C: Blood / sex
Path	Viral infection of liver parynchma
Clx	·       Jaundice + Fever ·       Dark urine ·       HSM ·       weight loss, and fatigue
Dx	·       LFT: ⤴️ direct bilirubin / ALP / AST&ALT ·       Serology (for all except hep B): ·       IgM antibody for the acute infection ·       IgG antibody to detect resolution of infection. ·       Disease activity of hepatitis C is assessed with PCR for RNA level ·       Hep B: u know it
Tx	·       Hepatitis A and E resolve spontaneously ·       Tx only Hep C: ·       Genotype 1: ledipasvir and sofosbuvir ·       Other genotype: sofosbuvir and velpatasvir ·       Tx of Chronic Hep B: ·       positive for e-antigen with an elevated level of DNA polymerase, treatment is any one of the following: entecavir, adefovir, lamivudine, telbivudine, interferon, or tenofovir.
Extra	·       If pt has fibrosis on Bx (Hep b / c): start tx ·       In Hep C: If the PCR-RNA viral load is elevated, patients should be treated.

Hepatitis C
Dx	·       IgG + IgM ·       PCR RNA ·       Everyone born between 1945 and 1965 is tested for hepatitis C regardless of risk factors. ·       Viral load testing has nearly eliminated the need for liver biopsy.
Tx	·       If the PCR-RNA viral load is elevated, patients should be treated. ·       If there is fibrosis on liver biopsy, initiating treatment becomes more urgent ·       Genotype 1 is treated with sofosbuvir + ledipasvir orally for 12 weeks. ·       The other genotypes are treated with sofosbuvir and velpatasvir orally. ·       Interferon is only used in treatment failure.